JP2001262338A - Sputter film deposition system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a system by which a thin film having the same composition as that of a target material can be grown, and a thin film excellent in quality can be grown. SOLUTION: In this system in which gas is introduced into the inside of a reaction vessel 1 to hold the pressure to the low one, high voltage is applied on the space between a substrate 5 and a target 7 arranged oppositely to generate plasma, and the atomic target material scattering in the case cations in plasma are collided against the target 7 is deposited on the substrate 5 to form a thin film, the back of the target 7 is provided with a magnet device in which a generated magnetic field distribution controlling function is imparted, and the magnetic field is formed on the space between the substrate 5 and the target 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a sputter film forming apparatus for forming a thin film such as a semiconductor device.

[0002]

2. Description of the Related Art FIG. 3 is a longitudinal sectional view showing an example of the basic structure of a conventional sputter film forming apparatus of this kind. In the figure, 1
Is a reaction vessel, 2 is a gas inlet for introducing a gas such as argon or oxygen into the reaction vessel 1, and 3 is a vacuum exhaust port for evacuating the inside of the reaction vessel 1 to a vacuum. An anode 4 and a cathode 6 are installed inside the reaction vessel 1 so as to face each other. A substrate 5 for forming a film is formed on the anode 4, and a target 7 is arranged on the cathode 6. The cathode 6 is an insulating structure 8
Is electrically insulated from the vessel wall of the reaction vessel 1 by
Further, it is cooled by cooling water to remove heat generated by sputtering.

In this configuration, for example, argon is introduced from the gas inlet 2 and exhausted from the vacuum exhaust port 3 to make the inside of the reaction vessel 1 an argon atmosphere of about 0.1 to 10 Pa. When a DC voltage of several hundred V to several thousand V is applied between the electrode and the cathode 6, a glow discharge is generated between the electrodes, and a plasma region and a cathode potential drop region are formed as schematically shown in FIG. . The plasma region consists of argon cations and electrons. The argon cations in the plasma are accelerated toward the cathode 6 by the cathode potential drop near the cathode, and collide with the surface of the target 7. At this time, the material forming the target 7 becomes atomic and pops out from the surface. Some of the atoms of the target material projecting from the surface reach the substrate 5 disposed on the anode 4 and deposit there, forming a thin film of the target material.

As described above, in the sputtering film forming apparatus, cations obtained by glow discharge are caused to collide with a target,
The protruding sputter material is deposited on the substrate to form a thin film. However, in the apparatus having the configuration shown in FIG. 3, the growth rate of the thin film is slow.
A so-called magnetron sputtering film forming apparatus has been developed. FIG. 4 is a longitudinal sectional view showing a basic configuration example of a main part of a magnetron sputtering film forming apparatus. FIG. 1 shows an anode 14, a substrate 15, a target 17 serving as a cathode, and a magnet device for generating a magnetic field disposed on the back surface of the target 17 of the magnetron sputtering film forming apparatus. The magnet device is a housing 23
The permanent magnet 20 and the magnetic path constituting member 21 are housed in the inside of the container, and are connected to the opening of the reaction vessel 11 via an insulator. A target 17 is attached to the lower end of the magnet device, and is configured to supply cooling water through a pipe inserted into the housing 23 via an insulator in order to suppress heating of the target 17 due to sputtering. . The permanent magnet 20 at the center and the permanent magnet 20 at the outer periphery are assembled so that the pole directions are opposed to each other as shown in the figure, whereby a magnetic field is formed in the plasma region as shown by the magnetic force lines in the figure. When a magnetic field is present in the electric field in this manner, electrons move in a cyclotron motion. In particular, a large amount of electrons are trapped in a region where the magnetic field is perpendicular to the electric field, that is, a region where the magnetic field is parallel to the surface of the target 17, and Is enhanced. For this reason, a large amount of cations collide with the surface (portion A in FIG. 4) of the target 17 facing this region, and spatters are efficiently generated, so that a so-called erosion area is formed. That is, in this type of magnetron sputtering film forming apparatus, atoms of the target material are scattered mainly in the erosion region, and a large amount of the scattered atoms is deposited on the substrate 15, so that a film can be formed at a high speed. .

[0005]

However, in a sputtering film forming apparatus, when a compound such as an alloy or a composite oxide is formed, the composition of the formed thin film deviates from the composition of the target material. It often happens. The first cause of the shift is that the sputtering rate and the bonding energy are different depending on a plurality of atoms of the target material, so that the ratio of the atoms scattered from the target is different from the composition of the target, or the adhesion rate to the substrate is low. It depends on the atom. As a method of avoiding a shift in the composition of the thin film due to such a cause, a method of performing sputtering by shifting the composition of the target material in advance is used. In this case, since the target is not a pure substance, purity, density, etc. In this case, the quality of the target is deteriorated, which is not preferable.

[0006] The second cause of the occurrence of the composition deviation of the thin film is as follows.
That is, the distribution in the scattering direction of atoms sputtered from the target differs depending on the atoms forming the target. As a way to avoid this shift, a method of rotating the substrate in a planetary rotation and depositing and averaging the atoms flying from a wide direction is adopted, but it includes atoms that scatter a lot in the direction parallel to the target surface In such a case, it is difficult to effectively suppress the displacement.

The present invention has been made in view of the current state of the art of such a sputtering film forming apparatus, and an object of the present invention is to grow a thin film having the same composition as that of a target material, and An object of the present invention is to provide a sputtering film forming apparatus that can use a target made of a pure substance.

[0008]

In order to achieve the above object, according to the present invention, a gas such as argon gas is introduced into a reaction vessel in which a substrate and a target are arranged to face each other, and the substrate and the target are connected to each other. A high voltage is applied to generate a plasma of the introduced gas, and the cations in the obtained plasma collide with the above target, thereby depositing an atomic target material on the substrate to form a thin film. In the sputter film forming apparatus to be formed, on the back of the target,
A generated magnetic field distribution which is provided with a magnet device for forming a magnetic field between the substrate and the target, and which can be executed by adjusting the arrangement position of at least two or more concentrically arranged permanent magnet groups in the magnet device An adjustment function is provided.

As described above, in the sputtering film forming apparatus of the type in which the magnet device is arranged on the back surface of the target and a magnetic field is formed between the substrate and the target to increase the density of the plasma, as described above, Sputtering occurs around an erosion region close to a magnetic field parallel to the magnetic field, and scattering of atoms of the target material occurs. on the other hand,
If the target contains two metal atoms, such as SrTiO ₃ , the Sr and Ti atoms will scatter from the target, but the distribution in the scattering direction differs depending on the atom, so the Sr and Ti atoms depend on the scattering angle. Are different. That is, as schematically shown in FIG.
Scatters relatively isotropically, whereas Ti scatters a lot in the vertical direction, so the ratio of Ti is relatively high in the vertical direction, and the ratio of Sr increases as the inclination angle to the vertical direction increases, In the direction of the illustrated angle α, the ratios of Sr and Ti become almost equal. Further, when the inclination angle is further increased, the ratio of Sr is relatively increased.

Therefore, as shown in FIG. 6, in an apparatus in which a target and a substrate are incorporated with an interval h,
The erosion region A may be set so that the angle between a straight line connecting the erosion region A formed on the target and the center of the substrate and the surface of the target is the above-mentioned angle α. The magnet device provided in the sputter film forming apparatus of the present invention is provided with at least two or more permanent magnet groups, and the generated magnetic field distribution can be adjusted by adjusting the arrangement position thereof. Thus, the erosion area A can be set by determining the distance D. Thereby, a thin film having the same composition as the target material can be formed on the substrate.

In addition, three kinds of constituent metals such as (Ba, S
r) When TiO ₃ is used as a target, Ba, S
The three types of metal atoms, r and Ti, are scattered, and the distribution in the scattering direction is different for each metal. In this case, three permanent magnet groups are arranged concentrically while maintaining an appropriate interval. By setting two erosion areas A1 and A2 having radii D1 and D2 as shown in FIG.
The three kinds of metal atoms Ba, Sr, and Ti are scattered to the center of the substrate at the same amount, and the composition of the thin film formed on the substrate can be adjusted to be the same as the composition of the target material.

When a film containing two metal atoms, such as SrTiO ₃ , is formed, it is necessary to adjust the distance h between the target and the substrate in place of the preparation of the erosion region, ie, the preparation of D in FIG. Can also make the composition of the thin film the same as the composition of the target material.
a, Sr) When three kinds of metal atoms such as TiO ₃ are contained, it is impossible to equalize the composition of the thin film only by adjusting the distance h between the target and the substrate. Adjustment of the magnetic field distribution is required.

[0013]

FIG. 1 is a longitudinal sectional view showing a basic structure of an embodiment of a sputter film forming apparatus according to the present invention. The configuration of this embodiment is characterized in that a magnet device 30 provided with a generated magnetic field distribution adjusting function is provided on the back surface of the target 7. In this apparatus, a permanent magnet inside the magnet device 30 is arranged so that a magnetic field distribution in which an erosion region of the target 7 is formed at a predetermined position is obtained near the surface of the target 7, and gas is introduced from the gas inlet 2. The reaction vessel 1 is evacuated and evacuated from the vacuum exhaust port 3 to make the inside of the reaction vessel 1 a depressurized atmosphere of a gas such as argon.
A high voltage is applied between the substrate 7 and the target 7 to cause discharge, and atoms scattered from the target 7 by sputtering are removed from the substrate 5.
To form a desired thin film.

FIG. 2 is a longitudinal sectional view illustrating a specific configuration inside the magnet device 30 provided with the generated magnetic field distribution adjusting function shown in FIG. 2A and 2B show a configuration in which an annular erosion region is formed on the target 7 by two permanent magnet groups 20. In the drawing, 6A has a cooling pocket formed by cooling water supplied from the outside. 20 is a permanent magnet, 21 is a magnetic circuit component, 2
4 is a support member. The difference between (a) and (b) in FIG.
The position of the erosion region formed by changing the installation position of the outer permanent magnet group 20 is different.

According to a thin film growth experiment using SrTiO ₃ as a target by the present inventor, the distance between the target and the substrate is
The permanent magnet group inside the magnet device 30 was arranged so that an erosion region having a radius of 27 mm was formed on the target, the substrate temperature was set to 400 ° C., and argon gas and oxygen gas were introduced into the reaction vessel. When the film was formed while maintaining the pressure at 0.2 Pa, the composition of the thin film was such that the proportion of Ti was too large as compared with Sr. A simulation was performed in consideration of the angle dependence of the scattering direction due to the sputtering of Sr and Ti, and the permanent magnet group inside the magnet device 30 was rearranged so that an erosion region having a radius of 35 mm was formed on the target. According to the film formation performed while maintaining the target material, the same Sr and T
It was possible to grow SrTiO _{3 in} which the ratio of i was 1: 1.

FIG. 2C shows a configuration in which three annular erosion regions are formed on the target 7 by three permanent magnet groups 20. As already mentioned,
For example, when growing a substance containing three constituent metal atoms such as (Ba, Sr) TiO ₃ , the permanent magnet group inside the magnet device 30 is arranged such that two annular erosion regions are obtained. By doing so, a thin film having the same composition as the target can be grown.

[0017]

As described above, according to the present invention, the sputter film forming apparatus is configured as described in claim 1, and further configured as described in claim 2 or 3. A thin film having the same composition as the target material can be grown on the substrate. Therefore, a pure substance can be used for the target, and a high-quality target can be used, so that a sputter film forming apparatus capable of growing a thin film having excellent quality can be obtained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a basic configuration of an embodiment of a sputter film forming apparatus of the present invention.

FIG. 2 is a longitudinal sectional view showing a specific configuration example of the inside of the magnet device 30 with a generated magnetic field distribution adjusting function shown in FIG.

FIG. 3 is a longitudinal sectional view showing a basic configuration example of a conventional sputter film forming apparatus of this type.

FIG. 4 is a longitudinal sectional view showing a basic configuration example of a main part of a conventional magnetron sputtering film forming apparatus.

FIG. 5 is a characteristic diagram showing a difference in the scattering direction distribution of Sr and Ti atoms in the SrTiO ₃ target.

FIG. 6 is a layout diagram showing a relationship between an erosion region A and a substrate where constituent metal atoms are formed on two types of SrTiO ₃ targets.

FIG. 7 is a layout diagram showing a relationship between erosion regions A1 and A2 formed on a (Ba, Sr) TiO ₃ target having three kinds of constituent metal atoms and a substrate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reaction container 2 Gas inlet 3 Vacuum exhaust port 4 Anode 5 Substrate 6A Cathode 7 Target 9 High voltage power supply 20 Permanent magnet 21 Magnetic circuit component 24 Supporting member 30 Magnet device (with generation magnetic field distribution adjusting function)

Continued on the front page F term (reference) 4K029 BA50 CA05 DC40 DC43 DC46 5F045 AA19 AC11 AC16 AD08 AE15 BB04 BB16 DP04 EB02 5F103 AA08 BB22 BB60 DD30 NN06 NN10 RR04 RR06

Claims (3)

[Claims] 1. A gas such as an argon gas is introduced into a reaction vessel in which a substrate and a target are arranged facing each other, and a high voltage is applied between the substrate and the target to generate plasma of the introduced gas. In a sputtering film forming apparatus for forming a thin film by depositing an atomic target material generated when cations in the obtained plasma collides with the target, and forming a thin film on the substrate, And a magnet device for forming a magnetic field between the two, and the magnet device has a function of adjusting a generated magnetic field distribution. 2. The sputter film forming apparatus according to claim 1, wherein the function of adjusting the generated magnetic field distribution of the magnet device is obtained by adjusting the arrangement position of the permanent magnet group. 3. The sputter film forming apparatus according to claim 2, wherein said magnet device includes at least two or more concentrically arranged permanent magnet groups.